My wife bought this fish about a month ago. It's her new baby, feeds it, changes his water regularly (100%). I was looking at him this evening and he seems to look slightly dull and has black spots. He's very active, blows bubbles, eats like a piggy when he's fed, and over all seems healthy. If I understand correctly these little guys are hard to keep around. Just wanted to see if its just his natural colouring or if he's sick.

Would need pictures. However, his behavior sounds like he is doing just fine. Bettas are very hardy, so don't worry too much even though you want to take some caution. Such that I would be more cautious about 100% water changes. Try to decrease it to 3/4 at least. Depending on what you have in there, my tanks are bare and free of everything except plants. So I normally take the first half, which seems to be the cleaner of the two, keep that, and dump the rest out. Then I add the two water together and slowly acclimate the betta to the water again. Though this might work for you now, somewhere along the road you are most likely going to question why your betta is clamping fins or sick lol. Just my half penny.